Subject: [PATCH V6 0/6] iommu/msm: Add DT adaptation and generic bindings support

From: [email-masked] (Sricharan)
Date: Fri, 12 Aug 2016 19:18:17 +0530

Hi,

>>>>>> btw, the current state, at least on linaro integration branch, fault
>>>>>> handling doesn't work so well (ie. device never gets resumed).. which
>>>>>> is a bit unfortunate for a gpu (and results in a *lot* of rebooting on
>>>>>> my part when debugging userspace).  I haven't had time yet to compare
>>>>>> to the ancient downstream driver, but not sure if you have any ideas?
>>>>>>
>>>>>> I guess probably disabling stall on fault would help.  But I'm not
>>>>>> even getting the "Fault occurred in context.." prints.  Seeing the
>>>>>> fault iova is pretty useful since that plus gpu cmdstream trace helps
>>>>>> me figure out which texture/etc is being accessed out of bounds.
>>>>>
>>>>>fyi, it looks like it is not getting any fault irq..  it's *possible*
>>>>>that I screwed up the irq #'s when translating from downstream, so you
>>>>>might want to double check that.  I thought I had it right, I assume I
>>>>>would have noticed during piglit runs if fault recovery wasn't working
>>>>>(since the result is that *everything* after the faulting test would
>>>>>have failed since gpu is wedged with no access to memory), but it was
>>>>>long enough ago that I can't claim that definitively.
>>>>>
>>>>>If you need an easy way to trigger a gpu fault, msmtest is a good way,
>>>>>change this line:
>>>>>
>>>>>  https://github.com/freedreno/msmtest/blob/master/msmtest.c#L247
>>>>>
>>>>>from OUT_RELOC() to OUT_RING(ring, 0x00000000) will trigger a fault.
>>>>>
>>>>    So for the irq to be triggered, 'non-secure' irq line has to be
>>>>   populated in DT. There is a 'secure'and 'non-secure' irq lines for these iommus
>>>>   and  non-secure irq number is secure + 1. I tested this by having a 'return 0'
>>>>  from the msm_iommu_map (no mapping), and the faults were getting triggered.
>>>>
>>>>   Can you share me your dts data ?
>>>>
>>>
>>>I think this is what you want:
>>>
>>>https://github.com/freedreno/kernel-msm/blob/integration-linux-qcomlt/arch/arm/boot/dts/qcom-apq8064.dtsi#L2008
>>>
>>>I haven't tested a display fault, so I suppose it is possible that
>>>irq's are working for some iommu instances but not others?
>>
>> So in your DT, for gfx3d, the non-secure line is '70' and not '69' (This is secure) .
>>  Infact only '70' should be populated. The driver sets the irq line based on resource 0.
>>  This applies for all iommu nodes in your DT. (only the second irq line is needed).
>
>ahh, that would explain.
>
>Is it better to remove the extra entry, or should I just swap them
>all?  Ie. might there be some point in the future where the driver
>would want both?
    I feel better to have one. Not sure why the secure irq was added in first
    place in the downstream data and it would setup/handled by the TZ

Regards,
 Sricharan